So it’s been a while but I’m at the beginning stages of my next project. Just bought the donor bike and waiting for it to be transported interstate. Also waiting for the motor to be sent down from China so in the next couple of weeks I should be able to get started. Wohoo!

So I originally thought about doing an electric cafe racer motorbike as there’s something appealing about the way they strip everything back to just the essentials and expose the way it all works but I struggled with how to make the batteries look good. In general, EV batteries don’t look that good so I then changed tack and started looking a bikes with fairings so I could hide them! I’m also keen to use a hub motor to simplify the conversion and leave plenty of space for everything else. The other thing I am trying to do is make this as easy as possible to get an engineer’s certificate for the conversion. I spoke to a few engineers about the project and a common theme was don’t touch the brake system otherwise you’ll need to do brake testing which could add another $3,000

I had read good things about hub motors from QS Motor and they have a pretty extensive range of options. The bad thing was the hole pattern for mounting the brake rotor seemed non-standard so I thought I’d have to use the rotor that comes with the motor which is 220mm. So some more research to find bikes that use that size rotor on the rear and fairings to hide the batteries. The other thing was using a frame that has a cradle under the engine so when I take the the engine out it’s still structurally ok. Most new bikes seem to use the engine as part of the structure so that ruled out a whole lot of newer bikes. This really narrowed down the options so I finally settled on a late 80’s Yamaha FZR250 as my donor bike and proceeded to buy a swingarm and rear brake bits from a wrecker to do some prototyping.

Below are some photos of 3D printed custom axles to get everything fitting and the wheel centred and modifying the slots in the swingarm where the axle normally goes through into dropouts like on a push bike so I can get the motor in. On motorbikes the axle gets inserted through the swingarm into the wheel but on the QS hub motors the axle is fixed in the wheel.

I also tested where the rear rotor would end up relative to the existing brake calliper and mounting bracket setup. In the prototype below everything looked like it was going to line up but then I realised the wheel was a bit off centre! So after fixing that, I will now have to use an adapter plate between the motor and the brake rotor to line everything up ... which means I wasn’t limited to using a bike with the size of brake rotor that comes with the motor in the first place!

Because the axle is built into the motor and needs to be held firm while the motor spins, there will be a lot of torque where the axle passes through the swingarm. To make this stronger I’m going to use solid blocks of aluminium? inside the swingarm. The tolerances need to be quite tight as there are acceleration and regen torque forces that need to be counteracted.

This is the donor bike I just bought. The previous owner put a lot of TLC into it so it looks like it’s in really good condition. As mentioned I selected this bike because of the size of the rear rotor but turns out it’s a really good bike and one of the better 250’s from that era.

Yep for the most part.
The nominal for an LTO is usually 2.4V so 69V becomes 72V.
I did see they claimed 2.3V - not too sure why.

Just as a rule of thumb since it exists and are claiming it.https://www.zeromotorcycles.com/zero-srf/
Under full specs it says 12600Wh usable capacity and 82miles/132km highway usage(113kph).
This works out to 95Wh/km or about 25km range on the 30 cells.

The other side was 12600Wh and 161miles/260km for city usage.
This is 50Wh/km.
So the 30 cells of LTO 40Ah is 72V x 40Ah = 2880Wh x 0.8 DOD = 2304Wh / 50Wh = 46km.

So there is nearly double the difference depending on how you ride.
But at least it is a place to start.

Help prevent road rage - get outta my way! Blasphemy is a swear word. Magnetic North is a south Pole.

The other side was 12600Wh and 161miles/260km for city usage.
This is 50Wh/km.
So the 30 cells of LTO 40Ah is 72V x 40Ah = 2880Wh x 0.8 DOD = 2304Wh / 50Wh = 46km.

So there is nearly double the difference depending on how you ride.
But at least it is a place to start.

That’s great, thanks for clarifying. I briefly had a Fonzarelli and that got ~50km from a 1650Wh pack = 33Wh per km which is really impressive. It’s pretty light and more for city usage which helps it get those numbers. My bike will be a bit heavier but will be mostly city usage.

I ran some numbers for different battery options and based range on 60Wh/km. Let me know if anything looks horribly wrong. The cost I’ve used for the Leaf batteries is probably way too low as I can’t even find any in Australia!

Next steps are to install the brake and work out an adapter plate to attach the bike’s original brake rotor to the motor. Also need to make up some blocks to hold the axle in the swingarm and some kind of bracket to hold all of this so I can do some bench testing.

60 Wh/km is probably about right for a bike this size. My scooter is in that range, and even the electric Superbike will manage 60 Wh/km if you ride at road legal speeds. Looking forward to seeing this turn a wheel.

I briefly had a Fonzarelli and that got ~50km from a 1650Wh pack = 33Wh per km which is really impressive. It’s pretty light and more for city usage which helps it get those numbers. My bike will be a bit heavier but will be mostly city usage.

I ran some numbers for different battery options and based range on 60Wh/km. Let me know if anything looks horribly wrong. The cost I’ve used for the Leaf batteries

My Emax was same size as the fonzareli and use to get around 33wh/km too.

My Vectrix gets around 70wh/km around town and 85wh/km at 100kmh. I suspect my Vectrix is around same size as your project, though may be heavier as its battery is 95kg on its own.

The cost I’ve used for the Leaf batteries is probably way too low as I can’t even find any in Australia!

Yeah I bought leaf cells for my Handi and shortly after the market dried up.
Barring a few on fleabay at unrealistic prices.
Don't forget that the leaf cells are 2nd hand.

This is why this thread peaked my interest.http://forums.aeva.asn.au/viewtopic.php?p=72427#p72427
Nissan can obviously supply new packs at a good price.
Its just a case of loosening their tight fists.
Well I shouldn't say "Nissan" since they sold the battery manufacturing section off.

Would leaf cells actually fit your bike?

Help prevent road rage - get outta my way! Blasphemy is a swear word. Magnetic North is a south Pole.

Received the bike last week and started removing the ICE related bits that I won't be needing. One thing that I didn't expect to find was the coolant runs through the frame of the bike. There's a bolt on the lowest part of the frame used to drain the coolant out which I've done but now I'm wondering if the inside of the frame might start rusting without the coolant to protect it. Does anyone have any experience with this or thoughts on whether or not it could be an issue?